SABRE: Adding risedronate to anastrozole improved BMD in postmenopausal women with early breast cancer

In postmenopausal women receiving the aromatase inhibitor anastrozole for the treatment of hormone receptor-positive early breast cancer, the addition of the bisphosphonate risedronate to the treatment regimen had favorable effects on bone mineral density.

In the SABRE trial, researchers assigned patients to treatment groups based on risk of fracture. Thirty-eight patients were assigned treatment with anastrozole 1 mg per day and risedronate 35 mg per week (high-risk group); 154 patients were randomly assigned anastrozole plus risedronate or anastrozole plus placebo (moderate-risk group); and 42 patients were assigned anastrozole alone (low-risk group).

In the high-risk group, assigned risedronate, the change in bone mineral density from baseline to two years was 3% for lumbar spine and 2% for total hip. Conversely, in the low-risk group treated with anastrozole alone, the estimated change in bone mineral density was –2.1% for lumbar spine and –0.4% for total hip.

In the moderate-risk group, the change in bone mineral density for lumbar spine was 2.2% in those assigned risedronate vs. –1.8% for those assigned placebo. The change in bone mineral density for total hip was 1.8% in those assigned risedronate vs. –1.1% for those assigned placebo.

Treatment was well-tolerated with adverse events similar between groups; safety profiles for anastrozole and risedronate were consistent with those observed in findings from previous studies, according to the researchers.

Van Poznak C. J Clin Oncol. 2009;doi:10.1200/JCO.2009.24.5902.